This invention relates to livestock scales in general and particularly to such scales having scale arm arrangements and apparatus for limiting horizontal movement of a weighing platform.
It is desirable in raising livestock to routinely determine the weight of the animals. For example, pig litters are routinely weighed to chart weight gains of the entire litter, as when utilizing a system termed "Sow Productivity Indexing". A deviation from a normal weight gain pattern can indicate that at least some of the pigs are not healthy, and appropriate action can be taken if a deviation is noted.
Further, as the animals grow the type of feed is changed at certain stages. Also, by weighing the animals, the owner can select the optimum size at which to send the animals to market for sale.
Various prior devices have been directed to weighing livestock, but have been found to be inefficient or unsatisfactory for weighing litters for various reasons. For example, other types of scales often must be machined to within certain close tolerances. They generally have critical dimensions, typically four, that have to be monitored precisely, with a micrometer, for example. Examples of these scales are the torsion tube type, the knife-edge type, and the torque suspension type. These and other types of scales have generally been found to be difficult to operate and calibrate for accurate measurement. Certain scale arm mechanisms have previously been disclosed, such as U.S. Pat. No. 446,309 issued to West. Although scale arm arrangements are generally preferable to the other types for weighing livestock, previous such arrangements have also generally been shown to be inadequate. For example, the weight-indicator means must necessarily be connected to the scale arms at their central juncture. Thus, there is no room for adjustment to accommodate different weight-indicating means that are set up in a different porportion to the weight received on the weighing platform. Also, there is no provision for precise calibration of the connection of the scale arm and the weight-indicating means after assembly of the scale parts where the parts are not precision made.
It is also generally desirable to manufacture an overall scale apparatus that is relatively small, yet still has large litter capacity, and not bulky to both make the apparatus easier to move about and to reduce the cost. Further, because live and mobile animals are being weighed, it is preferable to provide the apparatus with a restraint system to inhibit horizontal movement of the weighing platform relative to the support apparatus so that animal jostling would not affect the indicated weight or damage the apparatus. It is also desirable to isolate the weighing mechanism from the corrosive excretions of the animals being weighed.